A Presentation Of Transportation Of concrete

P R E S E N T E D T O : S U B M I T T E D B Y

P N D A R D E P R I TA M D U B E Y

H . O . D O F C I V I L D E PA RT M E N T

Transporting Concrete

– Transporting: concrete produced from a mixer is required to be transported to the forms for placing .– This handling tends to produce segregation and loss of slump, if the distance is long. – Methods of transporting and placing, which permit the use of drier mixes are better.

Transporting Methods

Method of transporting and placing concrete which are used widely, are:

Discharge directly in to forms through short chute or for a very small lead manually in containers.

By barrows: Wheel burrows and handcarts.

Power barrows or power buggies

Dumpers and trucks (agitating or non agitating)

Transporting Methods

Monorail system

Elevating towers and hoists

Skips operated by cranes or overhead cable ways

Belt conveyers and Boom conveyers

Truck mixers & Agitator Trucks

Tremie

Concrete pumps and pneumatic placers >Any combinations of above

Direct Discharge, Manual Transport in containers and Short Chutes

Free fall of concrete over a height of 2m is to be avoided. >Short chutes with proper lower end treatment are simple to use and economical.

metallic, half round in section, stiffened at places may last to handle about 1500m3 of concrete.

 Long chutes are less desirable

 

Burrows & Dumper trucks

Manual wheel burrow capacity up to 80 kg of concrete.

Power Burrows up to 800 kg and 300m haul and can haul to a 20 % gradient.

Dumpers and Trucks (Horizontal transport) are used for long hauls. Because of the jolting on the ground, ordinary trucks and dumpers tend to cause segregation of concrete during transit

Dumper trucks

Monorail System

Monorail system needs a track and consists of a power wagon mounted on the single rail track, which can move at a speed of 80-90 m/min.

Segregation of concrete may take place due to jolting of concrete in the wagon over each rail joints, hence wet mix are generally unsuitable for monorail transport. when the rail track runs over the slab form, the wagon can directly discharge on the form.

Elevating Tower and Hoists (Vertical transport)

Elevating towers are used for lifting concrete buckets, which can be distributed using a chute or by other means such as barrows, etc.

Hoists operate on a similar principle. A cantilever platform hoist operates along a steel lattice mast.

Concrete skip can be used directly, that can tilt and discharge the concrete on some distribution system.

Hoists (Vertical transport)

Cranes and Cableway (Two or three dimensional transport

Cranes or cableways may be used for three dimensional transport of concrete. Cable way is useful in river valley projects. Cranes of various types are also useful in high rise building construction in congested sites.

Depending upon the site, cranes may be any one of the following types such as derrik crane, tower crane, crawler mounted, or wheel mounted, or a hydraulic crane

The main consideration in selecting the crane is height and radius of operation

Cableway

Belt Conveyor

Belt conveyors needs small power.

Discharge can be as high as 115 cubic m/hour on a narrow strip of belt The main consideration in selecting the crane is height and radius of operation.

Conveying concrete through a limited elevation of 30 degree is possible.

For wet mixes the capacity of the belt is reduced as the inclination through which concrete can be lifted is also lowered

Under water Concreting

Under water placing of concrete poses a number of problems, as concrete cannot be compacted and concrete cannot be compacted and concrete may get mixed with water. Whenever, possible under water connecting, is to be avoided.

To overcome the problems mentioned above, concrete must be self compacting and wet enough to flow under its own weight.

1) pre packed or grouted concrete 2) Tremie or bucket 3) Pumping 4) Dumping by bags.

Under water Buckets

Tremie

Any query!!!

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